Automatic telephone system



ame 10 1924;

R. MERCER AUTOMATIC TELEPHONE SYSTEM 1 Filed March 12. 1921 inuen Ur-Emhard Harmer Patented June; 10, 1924.-

A 21,497,459 PATENT OFFICE.

RICHARD MERCER, OF LIVERPOOL, ENGLAND, ASSIC'NOR TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

.AUTOMATIC TELEPHONE srs'rma.

Ap'plicationflled March 12, 1921. Serial No. 451,903.

To all whom it may concern: Be it known that .I, RICHARD MERCER, asubject of the King of Great Britain and Ireland, and a resident ofLiverpool, England, have invented certain new and usefu Improvements inAutomatic Telephone Systems, of hich the following is a specification.

The present invention relates to improvements in or relating totelephone or like sys-' tems and has for its object improvedarrangements whereby calls may be dealt with in their proper sequence.More particularly, the invention relates to arrangements in connectionwith interjunction wo1'ki11g between automatic and manual exchangeswhere the-calls from the automatic subsc'riber aresetup on register setsand subsequently brought to the attention of anoperator.

One ofthe features of the present inven tion is an arrangement wherebythe calls are grouped into their proper sequence, that is, 1n the orderin which they arrive prior to the operation of the register sets, whilethe stored up calls are. dealt with in turn by a step by step switchingdevice which might either-consist of a mechanical step by step switchor.a chain of relays adapted to be operated in succession;

A second feature of theinvention consists of a novel arrangement forgrouping the calls into a definite orderusing rotary line switches ofthe type which remains on the contact last used. A third featureconsists of relay switching devices for automatically transferring thestored calls to an indicator or causing the illumination of lamps'to en=able the o erator to ascertain the junction seize reglster sets insetup. Fig. 4 represents the contact spring assembly of a relay employedin Figs, 1 and 3,

1 although it will iwiper 17 is resting Referring to Fig. 1, Crepresents a rota line switch of the type in which the wipers remain onthe contacts last used which, it is assumed, is associated with ajunction line,

he understood that this application is only ple, while B represents aregister set of which only part is'shown. When the junction line isseized, the lead 11 is connected to earth,.by arrangements wellknown tothose versed in the art, so that a circuit is closed through the backcontact of armature 12 of relay 13, through relay 14 to battery. Relay14 energizes and at its armature 15connects earth to one side of relay13, while at its armature 16 it connects the wiper 17 through the backcontact of armature 18 to the other side of relay 13 which is alsoconnected to the magnet 19. The operation consequently depends uponwhether the on an earthed contact or not. If it is rest ng on anearthedcontact, then the relay. 13 will be short circuited and themagnet 19 will be operated to advance the wipers one step, thisoperation will be repeated if the next contact wiper 17 comes in contactwith is engaged, but eventually, however, an idle line will be reachedwhen the wiper 17 will not rest on an earthed contact. Consequently,relay 13 will energize in series with magnet 19, magnet 19 will not,however, energize in this circuit owing to relay 13 having a highresistance. The energization of relay 13 at armature 18 connects earthto the test wiper 17, at armature 12 the earth on conductor 11 isconnected through wiper 20 to relay 21 and-battery, at armature 22,relay 13 looks itself energized to lead 11. Relay 14 will fall back onthe attraction of armature 12. The lead 23 is extended through armature24 of relay 13 to wiper 25 and its corresponding contact,

armature 26 of relay 21 and its working contact, series relay 27 andmagnet 28 of the first of a series of step by step switches adapted toregister the number of theialling party. As soon as the subscriber,dials the digits which have to bedescribed byway of exam- I stored,earth im ulses are transmitted over I the lead 23, there y causing theenergization of series relay 27 and magnet 28 which latter causes thewipers 29 and 30 to step round a number of steps corresponding to t enumber of impulses transmitted over lead 23. On the first impulse, relay27 is energized and the wiper 29 moved to the first step.

Wiper 29 thereby closes. a circuit for relay 31 which energizes anddisconnects the mpulse lead at armature 32. The operat ng circuit is,however, maintained, through ar mature 32 and. its working contact. Onthe completion of the first series of impulses the relay 27 deenergizes,while. the relay 31 re mains energized' Consequently, the i m-"pulsecircuit is continued from armature 26 and its working contactthrough armature 32 and its working contact, armature 33 and its restingcontact to the next step by step switch which-corresponds ineveryrespect. to'that just described and serves to record the second impulse.A similar arrangement of'relays. 31 and 27 is provided with this switch,which enables the impulse circuit to be transfe-rred'to a third switchwhen the previous digit has been completed. Consequently, as many digitsmay be stored as is desired. 1

On the relay 27 of the last digit switch fallingback an earth is placedon lead 34. This lead causes theenergization of relay 35 and also lightsthe register lamp 60.

The above circuit arrangements, which are disclosed in the pendingapplication of -Martin'et al., Serial No. 367 ,850, filed March 22.

and suitable circuit connections.

tracing the chain circuit of the relays 21,

each of which corresponds to adifferent register set, that when-onerelay .21 is ener-g.

gized, say the first relay, an earth may be traced through armature 38,lead 39 through each ofthe armaturesAO of the remaining relays 21 to allthe contacts of thebank 37 except the second. Thus it will be seen thaton a second call coming in, the wiper 17 of the switch used will'findearth on the con tacts corresponding to all register sets except thesecond, which, itmust consequently come to restupon.

The third call. coming in, even ifthe call on No. 1 register set hasbeen attended to but No.2 is still awaiting attention, will be allocatedto the third position and so on.

, Consequently,'every call coming in before others have been attended towill be arranged I in a definite order. If, however, only one call comesin at once, then the rotary switches seized will not have to hunt, asall contacts adapted to be swept over by 17 will be disconnected fromearthr Consequently, it will be appreciated, that by this means, thecalls will be arranged to seize register sets in the order in which theytact, armature 42 and its working contact,

resistance 43, relay 36 to earth. Although branch circuits are alsoclosed for the other relays 36,'tli'ese branch circuits are opened atthe back contact of armature 45 as soon as the first relay starts topull up. Accordingly, only relay36 of the first register set will fullyenergize. On. energizing, this relay closes a locking circuit for itselfat arma ture 44, at armature 15 it connects earth to a common leadconnected similarly to the armature's 45 of the relays 36 of the otherregistersets, while at its, armature 41-6 it disconnects earth from allthe other re lays 36.

Referring to Fig. 1, it will be seen that in the register set. taken byway of example, relay 36 also connects earth at its armature 47 toenergize the relays '48, of which one is provided'for each of theswitching units of a register set. The relays 48 are arranged to connectearth to the contacts selected-by the individual switchin units,wh'ichcontacts are connected in multiple with the corresponding contacts ofthe other register sets, to a bank of lamps common to an operators po-.

\ sition. These lamps are arranged in sets side by side, one set foreach switching unitrand have numbersthereon corresponding to theposition of the contacts in theswitch banks. As one terminal of eachlamp is permanently connected to battery, the'relays 48 on ener gizlngcause the number set up on the regis-' ter set to be immediatelydisplaycdtbefore the operator, while the last relay 48 connects earth tothe lead 49' which passes through the wiper 50V to the lead 51'toilluminate a lamp corresponding to the junction with which the rotaryswitch C is associated. The operatontherefore, sees the number of theparty required and the lamp lit at the junction at the same time andtherebyhas all the information necessary to enable her to complete theconnection. Since, the arrange ment for displaying register numbersforms no-part of the present invention, it has not been considerednecessary to show all the circuits concerned in detail,'but reference'is made to the hereinbefore cited application of 36 of the firstregister set.

, and fifth.

with. In order to prevent any attention, the second register set hadbeen taken into use and also the third, fourth Now on relay 36 of thefirst register set deenergizing, after the "operator had attended to thecall, only the relay 36 of the second register set will be able tooperate, as it will receive current from battery through armature 41 ofrelay 35 of the first register set and its resting contact througharmature 42 15 of relay 35 of the second register set, resistance 43,relay '36, back contact of armature -46 to earth.

The energizing battery of the relays 36 of the third, fourth, fifth andsixth register sets hasbeen removed by the armatures 41 of the relays 35of the second, third, fourth, Y

whichattention,

and fifth register sets, respectively, have calls stored up and awa'itinand battery is removed from tl ie common conductor at the back contactof armature 45' of relay 36 of the second register set as soon asthisrelay starts to pull up, as already explained in connection with relayThe second call is accordingly dealt'with as usual, after which on thedeenergization of relay 35 of the second register set, the third call isswitched over.

It will be assumed, that by now, two more calls have -come in on to thesixth and seventh register sets. The call coming on to the seventhregister set removes battery at armature 41 0f relay 35 of that set, so

that if a further call comes in which will be allocated tothe firstregister set, the rela 36 of that register set cannot energize until thelast register set has been dealt possibility of two calls being switchedover-at once on to the indicator which might arise by one of the callingpartles ceiver before beingattended to, the common lead connected to thearmatures .45 is provided so "that the relay 36 of all positions exceptthat in use will. be short ciircuited. i

It is also to be noted that this arrangement has the greatadvantage,'that if two parties are dialling and one should take a timeto dial than the other, then it is possible to attend .to the one. whohas completedhis dialling; first even although. he should be on theregister in advance'of the other party; for instance, assuming twosubscribers seize thesecond and third register sets,.but the subscriberwho has seized the third register set completes his dialling in a muchshorter time than the subscriber who has seized the second register set.The operator having dealt with No. 1 register set is then immediatelyswitched onto No.

hanging up his re-- register set interrupts 3 register set as the' relay35 of the second register set will not haveenergized; then if the'partyon the second register set completes his number, he will have'preferenceover anyone using, the fourth register set,

while the subscriber on the fourth register set would be attended tonext and the routine would go on in the same order as previouslydescribed.

In Fig. 4 the-arrangement of the spring contacts of the relay 36 areshown in operative relationship bywhich it would be appreciated that, onthe relay releasing the operations take place in substantially thefollowing order: Firstly the front contact of armature 45 breaks, thenarmature 46 makes contact; followed by armature 45 making contact withits back contact. I Or, considering the reverse operation, on the relayenergizing, the back contact of armature 45 breaks first, after which.armature -16 breaks its contact and then armature 45 closes its makecontact. Thisadjustment is necessary in order to avoid operating morethan one relay 36 at the same time, as will doubtless be understood fromthe previous explanation.

In further explanation, however, it may be pointed out more particularlythat it. is necessary to have the make contact of armature 45 closelast, or after armatur'es 45 and 46 have separated from their backcontacts, in

order to avoid grounding the common conductor by partially energizedrelays such as 36. before such relays are caused to fall back by theopening of the back contact of armature 45 or 46 of the relay 36 whichcompletely energizes. As to the necessity of having armature 45 separatefrom its back contact before armature 46 breaks its contact, thisadjustment becomes essential in a case where calls sixth, seventh, andfirst register sets, for example. W'hen the fourth register set isreleased, and relay 35 of such register set connects battery to relay 36of the fifth register-set, battery is also connected by way of the backcontact of armature 45' of this relay to relays 36 of the sixth,seventh, and first register sets. Relay 36 of the fifth the groundconnection to relays 36 of the sixth and seventh register sets at itsarmature 46, so there is no particular danger of these relays pullingup,

butit does not interrupt the ground connection to'rclay 36 of the firstregister set.

Onthecontrary, the last mentioned relay interrupts the ground connectionto the rela'y 36 of tlie'fifth register set: it is essential .35register set and performs other similar easily made and areentirelyefl'ective in preventing the difficult mentioned. I

It will be appreciated, that the invention is equally applicable to,mechanical call in- 5. dicators, as to luminous call indicators, forinstance, when a limited number of mechan ical call indicators areconnected by means of rotary switches .to junction lines, then they maybe arranged to close contacts. similar to the contacts closed by relay35, when all the digits of the num; her have been registered; then arelay equiv alent to 36 will be energizedswhich would be energized inthe order in which theregisters have been seized, as previouslydescribed.

This would effect the illumination of a lamp' local tovthe'mechanicalcall indicator and the illumination of a lamp local to theparticular junction line. Conveniently, lamps I such as 60 would becontrolled by the relay 36 and not by the springs operated on thestorage of a number, thereby indicating not only that a call is storedbut that a call is stored and should be attended to next.

It will be appreciated, therefore, by means of the arrangement shown inFigs.'2 and 3,. .the calls are first graded into a proper order,provided that they are not coming in one at a time when no orderingwould be so required, and they are subsequently. dealt 'with one at atime by means of relays and 36 and suitable interconnecting arrange-ments as shown. Relay 36 on energizing causes the energization ofrelays 48 inthe functions which have ferredto. i

Having now particularly described and ascertained the'nature of myinvention and; 40 in what manner the same is to be performed,

I declare that what I claim is 1. In a telephone system,huntingswitches, lines all normally selectable by'said switches, and means forcausing the remaining lines to .be selected in rotation whenever one ormore lines are in use.

2. In a telephone system, a plurality of lines, a plurality of huntingswitches adapted to select and connect with said lines at so random, andguarding circuits efi'ective only when one or more lines are connectedwith for causing subsequently operated switches to connect with lines inregular order. 3. In a telephone system, a plurality of. lines, aplurality of hunting switches having access to said lines in common,each switch having wipers which normally rest on the last selected line,and guarding circuits effective when any line is in use to cause subbeenpreviously resequently operated switches to select other lines inregular rotation.

4. In a telephone system, a plurality of hunting switches, a pluralityof lines accessible to said switches in common, all said lines beingnorinally available for selection, and means rendered effective when anyline is selected for rendering all other lines unselectable except theline next inorder after the one selected.

5. In a telephone system, a plurality of hunting switches, a pluralityof "lines acces sible to said switches in common, all said lines beingnormally available for selection, guarding circuits for renderingsaidlines unselectable, and a relay individual to each 7 line, each relayoperating when its associated line isselecte'd' to close the guardingcircuits. for another idle lines'except the line next in order.

i. The combination, with register sets all 801 normally selectable, ofmeans .for causing said sets to be selected in rotation whenever morethan one is used at the same time, and a consecution controller forcausing registered calls to be switched over to a display device one ata time. 7. The combination, with register sets all normally selectable,of means for causing saidscts to be selected in rotation whenever asetis already in use, and a consecution controller for causingregistered calls-to be switched over to a'display device in the order inwhich their registration is completed. provided only one register set ata time is occupied b 1 a completely registeredcall. 8. The com ination,with register sets all normally selectable, of means for causing saidsets to be selected in rotation whenever a set is already in use, aconsecution controller for causing registered calls to be switched overto a display device one at a time, and circuit arrangements in saidcontroller establishing a definite order'of preference between registersets occupied by ful ly registered calls which is independent of 106 theorder in which the registration of such calls is completed.

9. The combination; with register sets all normallyselectable, of meansfor causing said sets to be selected in.rotation whenever 110 a set isalready in use, a consecution controller for causing registered calls tobe switched over to a display device one at a time, and circuitarrangements in said con troller establishing a definite order ofprefl16 erence between the register sets upon which fully registeredcalls are waiting and giving such register sets preference over registersets upon which the calls are only partially registered. r 10. Thecombination, with a plurality of register sets and means for operatingthem to register called telephone numbers, of a consecution 'eentrollerfor causing registered numbers to be switched over to a display de- 125vice one at a time, said controller having circuit arrangements forestablishing a definite order of preference between said regismemee tersets with respect to the order in which any occupied register sets areassociated with the display device, and means effective in case all theregister sets become occupied at one time for destroying the establishedorder of preference to permit all said register sets to be associatedwith said display device before any particular set, which ordi' toregister called telephone numbers, of a start relay and a test relayindividual to consecution controller for causing registered numbers tobe switched over a display device one at a time, said controllercomprlsmg a each register set, a circuit for each start relay closedwhen the associated register set is occupied by a completely registeredcall,'a circuit for each test relay connecting one terminal thereofto-one pole of the battery, each such circuit including contacts on theassociated start relay and contacts on another start relay, a commoncircuit for connecfing the other terminals of all saidutest relays tothe other pole of the battery, and contacts on each test relay except"the last included in said common circuit whereby each test relay exceptthe last disconnects all-usu'cceeding test relays from the said otherpole of the battery.

Signed by me at February, 1921.

Liverpool this 4th day of

